Scouting

This build has a natural weakness to Roaches, it is vital to gauge the timing of any Roach Warren and any expansions. Roaches on the field will create problems for a 4 gate attack, and unless the Zerg takes a fast expansion, it is unlikely that an overwhelming numerical advantage can be had from 4 gates. Any aggression from Roaches can delay your attack so it is best to quickly transition into 3-gate/robo and prioritize an Immortal or two in order to mitigate this weakness and attack before Lair tech. Expansions by the Zerg player will limit his unit count and work in your favor, opening a timing window to attack before the Zerg realizes its economic advantage. Always explore the possibility of a proxy Pylon in the Zerg base, but realize that it is more difficult to execute due to Zerg's scouting options.

Execution

Once Warpgate research finishes, it is time to push out and attempt an attack. If a proxy Pylon was planted in your opponent's base you should move out any units towards it, leaving behind a Zealot and Sentry to prevent speedling counterattacks and begin warping in units inside their base.

Without a proxy, you should warp in around your base and push out toward them. A probe should advance with your army and set up a Pylon midway between bases or close to the enemy natural to reinforce your attack.

Aim to do significant economic damage, killing drones or Queens, or snipe an expansion. Accept losses to destroy a Hatchery, a units worth in drones, or tech building but do not overcommit in the event that the Zerg has heavily defended their main base.

Adaptation

If the Zerg is not prioritizing his economic development by expanding or building drones (and is less susceptible to this attack in the first place) you can poke at your opponent's base while expanding to your own natural and teching up. If your opponent sustains damage or holds you off they will be moving on teching past Lair if they haven't already. You will need to scout your opponents tech choices; an observer can be used if you have a Robotics Facility. If not, hallucinated Phoenixes are an excellent alternative. Be sure to keep your new base safe from sneaky counterattacks and prepare a response to your opponent's next moves.